Robot and joint device for the same

ABSTRACT

A humanoid robot including upper limbs, lower limbs, and a trunk. Hip joints which connect the lower limbs and the trunk each possess degrees of freedom provided in correspondence with a hip joint yaw axis, a hip joint roll axis, and a hip joint pitch axis. The humanoid robot is a leg-movement-type robot which walks on two feet. By arbitrarily offsetting the hip joint yaw axes in a roll axis direction, the effects of the movement of the center of gravity occurring when the mode of use of the robot is changed are accommodated to in order to flexibly balance the weights of the upper and lower limbs. The waist is made more compact in order to form a humanoid robot which is well proportioned and which makes it possible to prevent interference between the left and right feet when the direction of a foot is changed. Accordingly, a robot which moves naturally and in a way sufficiently indicative of emotions and feelings using fewer degrees of freedom is provided.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a realistic robot having astructure which emulates the mechanisms and movements of an organism,and, more particularly, to a leg-movement-type robot having a structurewhich emulates the body mechanisms and movements of, for example, ahuman being or a monkey, which walks while it is in an erect posture.

[0003] Even more specifically, the present invention relates to aleg-movement-type robot which walks on two feet while it is in an erectposture and which includes what one calls the upper half of the body,including the trunk, the head, the arms, and the like, provided on thelegs. Still more specifically, the present invention relates to a robotwhich can move naturally in a way close to that of a human being and ina way sufficiently indicative of emotions and feelings with considerablefewer degrees of freedom than the actual mechanism of, for example, thehuman body.

[0004] 2. Description of the Related Art

[0005] A robot is a mechanical device which emulates the movement of ahuman being by making use of electrical and magnetic actions. The termrobot is said to be derived from the Slavic word ROBOTA (slavishmachine). In our country, the use of robots began from the end of the1960s, most of which were industrial robots, such as manipulators andconveyance robots, used, for example, for the purpose of achievingautomatic industrial operations in factories without humans inattendance.

[0006] In recent years, progress has been made in the research anddevelopment of leg-movement-type robots which emulate the movements andmechanisms of the body of an animal, such as a human being or a monkey,which walks on two feet while it is in an erect posture. Therefore,there has been greater expectation for putting such leg-movement-typerobots into practical use. A superior feature of leg-movement-typerobots which move on two feet while they are in an erect posture is thatthey can walk flexibly, for example, up and down steps or overobstacles.

[0007] In the history of leg-movement-type robots, research regardingleg movement was started by studying as elemental technology legmovement using only the lower limbs. Accordingly, robots of this typeare not provided with all parts of the body which are positionedvertically.

[0008] For example, Japanese Unexamined Patent Publication No. 3-184782discloses a joint structure applied to the structural part below thetrunk of a robot which walks using the legs.

[0009] Japanese Unexamined Patent Publication No. 5-305579 discloses acontroller for controlling the walking of a leg-movement-type robot. Thecontroller disclosed in this document controls the walking of the robotso that the ZMP (zero moment point) matches a target value. The ZMP isthe point on the floor surface where the moment resulting from the floorreaction force when the robot walks is zero. However, as can be seenfrom FIG. 1 in this document, a trunk 24 on which the moment acts isformed using a black box, so that not all parts of the body areprovided. Therefore, the document is confined to proposing leg movementas elemental technology.

[0010] It goes without saying that the ultimate purpose of constructingleg-movement-type robots is to provide these robots with all parts ofthe body. More specifically, the ultimate purpose is to provide theserobots which walk while they are in an erect posture on two feet withthe lower limbs used for walking on two feet, the head, the upper limbs(including the arms), and the trunk which connects the upper and lowerlimbs. In such robots provided with all parts of the body, it ispresupposed that work is carried out by moving the two legs while therobots are in an erect posture. In all cases where such work is carriedout in the living space of human beings, it is necessary to control therobots so that the upper and lower limbs and the trunk move harmoniouslyin a predetermined order of priority.

[0011] Leg-movement-type robots which emulate the mechanisms andmovements of human beings are called humanoid robots. Humanoid robotscan, for example, help people in life, that is, help them in varioushuman activities in living environments and in various circumstances ineveryday life.

[0012] As is conventionally the case, leg-movement-type robots areroughly divided into those for industrial purposes and those forentertainment.

[0013] Industrial robots are intended to carry out various difficultoperations, such as in industrial tasks or production work, in place ofhuman beings. For example, they carry out in place of human beingsmaintenance work at nuclear power plants, thermal power plants, orpetrochemical plants, or dangerous/difficult work in production plantsor tall buildings. The most important theme is to design and manufactureindustrial robots so that they can be industrially used as specified andcan provide the specified functions. Industrial robots are constructedon the assumption that they walk on two feet. However, as mechanicaldevices, they do not necessarily have to faithfully reproduce the actualbody mechanisms and movements of animals, such as human beings ormonkeys, which walk while they are in an erect posture. For example, thefreedom of movement of particular parts (such as the finger tips), andtheir operational functions are increased and enhanced, respectively, inorder to produce an industrial robot for a particular use. On the otherhand, the freedom of movement of parts considered comparativelyunrelated to the use of the industrial robot (such as the head and arms)is limited or such parts are not formed. This causes the industrialrobot to have an unnatural external appearance when it works and moves,although it is a type of robot which walks on two feet. However, forconvenience in designing such a robot, such a compromise is inevitable.

[0014] In contrast, leg-movement-type robots for entertainment provideproperties closely connected to life itself, rather than help people inlife such as by doing difficult work in place of human beings. In otherwords, the ultimate purpose of producing robots for entertainment is tomake these robots faithfully reproduce the actual mechanisms of, forexample, human beings or monkeys, which walk on two feet while they arein an erect posture, and to make them move naturally and smoothly. Sinceentertainment robots are structured to emulate highly intelligentanimals, such as human being or monkeys, which stand in an uprightposture, it is desirable that they move in a way sufficiently indicativeof emotions and feelings. In this sense, entertainment robots whichemulate the movements of human beings are rightly called humanoidrobots.

[0015] In short, it is no exaggeration to say that entertainment robots,though intently called a leg-movement-type robot, shares the elementaltechnologies of industrial robots, but are produced for a completelydifferent ultimate purpose and uses completely different hardwaremechanisms and operation controlling methods to achieve the ultimatepurpose.

[0016] As is already well known in the related art, the human body has afew hundred joints, so that it has a few hundred degrees of freedom. Inorder to make the movements of leg-movement-type robots as close tothose of human beings, it is preferable that the leg-movement-typerobots be allowed to move virtually as freely as human beings. However,this is technologically very difficult to achieve. This is because,since one actuator needs to be disposed to provide one degree offreedom, a few hundred actuators needs to be disposed for a few hundreddegrees of freedom, thereby increasing production costs and making itvirtually impossible to design them in terms of, for example, theirweight and size. In addition, when the number of degrees of freedom islarge, the number of calculations required for, for example,positional/operational control or balance control is correspondinglyincreased exponentially.

[0017] Restating what has been stated in another way, humanoid robotsmust emulate the mechanisms of the human body equipped with a limitednumber of degrees of freedom. Entertainment robots are required to movenaturally in a way close to that of human beings and in a waysufficiently indicative of emotions and feelings with considerable fewerdegrees of freedom than the human body.

[0018] Leg-movement-type robots which walk on two feet while they are inan erect posture are excellent robots in that they can walk flexibly(such as up and down steps or over obstacles). However, since the centerof gravity of such robots is located at a high position, it becomescorrespondingly difficult to perform posture control and stable walkingcontrol. In particular, the walking and the posture of entertainmentrobots need to be controlled while they move naturally and in a waysufficiently indicative of emotions and feelings like intelligentanimals, such as human beings or monkeys.

[0019] Various proposals regarding the stable walking ofleg-movement-type robots have already been made. For example, JapaneseUnexamined Patent Publication No. 5-305579 discloses a leg-movement-typerobot which is made to walk stably by matching with a target value thezero moment point (ZMP), that is, the point on the floor surface wherethe moment resulting from the reaction force of the floor when the robotwalks is zero.

[0020] Japanese Unexamined Patent Publication No. 5-305581 discloses aleg-movement-type robot constructed so that the ZMP is either situatedin the inside of a supporting polyhedral (polygonal) member or at alocation sufficiently separated by at least a predetermined amount froman end of the supporting polyhedral (polygonal) member when a foot ofthe robot lands on or separates from the floor. As a result, even whenthe robot is subjected to an external disturbance, it is not affectedthereby in correspondence with a predetermined distance, making itpossible make the robot walk more stably.

[0021] Japanese Unexamined Patent Publication No. 5-305583 discloses thecontrolling of the walking speed of a leg-movement-type robot by a ZMPtarget location. More specifically, in the leg-movement-type robotdisclosed in this document, previously set walking pattern data is usedto drive an arm joint so that the ZMP matches a target location, and thetilting of the upper part of the body is detected in order to change theejection speed of the set walking pattern data set in accordance withthe detected value. Thus, when the robot unexpectedly steps on an unevensurface and, for example, tilts forward, the original posture of therobot can be recovered by increasing the ejection speed. In addition,since the ZMP can be controlled so as to match the target location,there is no problem in changing the ejection speed in a device forsupporting both arms.

[0022] Japanese Unexamined Patent Publication No. 5-305585 discloses thecontrolling of the landing position of a leg-movement-type robot by aZMP target location. More specifically, the leg-movement-type robotdisclosed in this document is made to walk stably by detecting anyshifts between the ZMP target location and the actually measuredposition and driving one or both arms so as to cancel the shift, or bydetecting the moment around the ZMP target location and driving an armso that it becomes zero.

[0023] Japanese Unexamined Patent Publication No. 5-305586 discloses thecontrolling of the tilting of the posture of a leg-movement-type robotby a ZMP target location. More specifically, the leg-movement-type robotdisclosed in this document is made to walk stably by detecting themoment around the ZMP target location and driving an arm so that, whenthe moment is produced, the moment is zero.

[0024] However, none of the above-described proposals mention anythingabout controlling the posture and walking of the robot while it ismoving naturally and in a way sufficiently indicative of emotions andfeelings like intelligent animals, such as human beings or monkeys.

[0025] A robot called WABIAN (Waseda Bipedal Humanoid) is disclosed in atreatise called The Development of Humanoid Robots Which Walk On TwoFeet (Third Robotics Symposia, May 7 and 8, 1998) by Yamaguchi et al.WABIAN is a complete humanoid robot which is provided not only with thelower limbs, but also with the upper limbs and the trunk, so that it isprovided with all parts of the body. WABIAN has been developed for thepurpose of producing a robot whose whole body moves harmoniously whileit is walking. FIGS. 13 and 14 are each schematic views of an assembledstructure of WABIAN. WABIAN has been designed and manufactured toovercome the problems involved in working while moving the whole bodyharmoniously. By controlling the ZMP and the yaw axis moment on the ZMPas a result of trunk or trunk/waist harmonious movement three axialmoment compensation operations, the robot may be made to walk while itslower limbs, finger tips, and trunk take any path of movement. Themechanical models illustrated in the figures use extra super Duraluminas main structural material, and has a total weight of 107 kg and anoverall length of 1.66 m when they are standing still in an erectposture.

SUMMARY OF THE INVENTION

[0026] Accordingly, it is an object of the present invention to providean excellent robot having a structure which emulates the mechanisms andmovements of the human body.

[0027] It is another object of the present invention to provide anexcellent leg-movement-type robot which walks on two feet and whichincludes the upper half of the body, such as the trunk, the head, thearms, etc., formed on top of the legs.

[0028] It is still another object of the present invention to provide anexcellent robot which can move naturally in a way close to that of ahuman being and sufficiently indicative of emotion and feelings with aconsiderable fewer degrees of freedom than a human being.

[0029] It is still another object of the present invention to provide anexcellent robot in which the posture and the walking thereof can becontrolled while the robot moves naturally and in a way sufficientlyindicative of emotions and feelings like intelligent beings such ashuman beings or monkeys.

[0030] To these ends, according to a first aspect of the presentinvention, there is provided a leg-movement-type robot which moves usinglower limbs. The robot comprises at least the lower limbs and a trunk.In the robot, a hip joint which connects the lower limbs and the trunkpossesses at least a degree of freedom in correspondence with a hipjoint yaw axis which is included in the hip joint. The robot furthercomprises an offset setting mechanism for arbitrarily offsetting the hipjoint yaw axis from the hip joint in a roll axis direction.

[0031] According to a second aspect of the present invention, there isprovided a leg-movement-type robot which moves using lower limbs. Therobot comprises at least the lower limbs and a trunk. In the robot, ahip joint which connects the lower limbs and the trunk possesses atleast a degree of freedom in correspondence with a hip joint yaw axiswhich is included in the hip joint. The hip joint yaw axis is offsetfrom the hip joint in a roll axis direction.

[0032] According to a third aspect of the present invention, there isprovided a leg-movement-type robot which moves using lower limbs. Therobot comprises at least the lower limbs and a trunk. In the robot, ahip joint yaw axis used for changing the direction of a foot tip isoffset from the location of a hip joint used for walking using the feet.

[0033] In the robots of the first to third aspects of the presentinvention, the amount of offset of the hip joint yaw axis from thelocation of the hip joint can be adjusted, so that it is possible toaccommodate to the effects of the movement of the center of gravityproduced in accordance with the mode of use of the robot in order toflexibly balance the weights of the upper and lower limbs. Therefore, itis possible to make the robot walk smoothly and naturally while it is inan erect posture.

[0034] By offsetting the hip joint axis, the size of the portion of therobot corresponding to the waist can be made smaller and compact, sothat it is possible to form a robot whose mechanical units aredimensionally proportioned with respect to each other. In other words,it is possible to form a robot which has a proportioned externalappearance close to that the natural form of the body of an animal(which walks while it is in an erect posture), such as a human being ora monkey.

[0035] When the joint yaw axis is offset from the location of the hipjoint in the backward direction or in the direction opposite to thedirection of movement, the location of the center of gravity of theentire robot is situated forwardly of the hip joint yaw axis. Therefore,in order to ensure stability in the pitch direction, the hip joint yawaxis is disposed behind the location of the center of each of the leftand right feet. In this case, even if the hip joint yaw axis is rotatedto change the direction of a foot, interference between the left andright feet can be reduced. In other words, since the width of the crutchdoes not need to be increased, the posture of the robot can be easilycontrolled in order to allow it to walk stably on two feet.

[0036] According to a fourth aspect of the present invention, there isprovided a leg-movement-type robot which moves using lower limbs. Therobot comprises at least the lower limbs and a trunk. In the robot, ahip joint which connects the lower limbs and the trunk possesses atleast a degree of freedom in correspondence with a hip joint yaw axiswhich is included in the hip joint. The robot further comprises anoffset setting mechanism for arbitrarily offsetting the hip joint yawaxis from the trunk in a roll axis direction.

[0037] According to a fifth aspect of the present invention, there isprovided a leg-movement-type robot which moves using lower limbs. Therobot comprises at least the lower limbs and a trunk. In the robot, ahip joint which connects the lower limbs and the trunk possesses atleast a degree of freedom in correspondence with a hip joint yaw axiswhich is included in the hip joint. The hip joint yaw axis is offsetfrom the trunk in a roll axis direction.

[0038] According to a sixth aspect of the present invention, there isprovided a leg-movement-type robot which moves using lower limbs. Therobot comprises at least the lower limbs and a trunk. In the robot, ahip joint yaw axis used for changing the direction of a foot tip isoffset from the trunk.

[0039] According to the robots of the fourth to sixth aspects of thepresent invention, the amount of offset of the hip joint yaw axis fromthe trunk can be adjusted, so that it is possible to accommodate to theeffects of the movement of the center of gravity in order to flexiblybalance the weights of the upper and lower limbs. Therefore, it ispossible to make the robot walk smoothly and naturally while it is in anerect posture.

[0040] The basic movement of, for example, a human being which walks ontwo feet is based on a forwardly tilted posture. Therefore, the robotcan easily exhibit the natural movement of a human being when the trunkwhich corresponds to the waist of a human being is disposed towards thefront. According to the robots in accordance with the fourth to the sixaspects, the walking of a human being can be faithfully emulated byoffsetting the hip joint yaw axis from the trunk in the roll axisdirection.

[0041] By performing an offsetting operation and moving the center ofgravity of the entire robot slightly forward, the robot can easilybalance itself in terms of its weight while it is walking.

[0042] According to a seventh aspect of the present invention, there isprovided a leg-movement-type robot which moves using lower limbs. Therobot comprises at least the lower limbs and a trunk. In the robot, thetrunk is offset from the lower limbs in a roll axis direction.

[0043] According to an eighth aspect of the present invention, there isprovided a leg-movement-type robot which moves using lower limbs. Therobot comprises upper limbs, the lower limbs, and a trunk. In the robot,the upper limbs are offset from the lower limbs in a roll axisdirection.

[0044] According to a ninth aspect of the present invention, there isprovided a robot of a type which spreads the legs thereof based onrotational degrees of freedom provided in correspondence with a hipjoint roll axis, a hip joint pitch axis, and a hip joint yaw axis. Inthe robot, at least the lower limbs and a trunk are mountedsubstantially vertically along a body axis direction, and the hip jointyaw axis is offset from the body axis by a predetermined amount.

[0045] According to a tenth aspect of the present invention, there isprovided a robot of a type which spreads the legs thereof based onrotational degrees of freedom provided in correspondence with a hipjoint roll axis, a hip joint pitch axis, and a hip joint yaw axis. Inthe robot, at least lower limbs and a trunk are mounted substantiallyvertically along a body axis direction, and the hip joint yaw axis isoffset from the body axis by a predetermined amount in a negative rollaxis direction.

[0046] According to an eleventh aspect of the present invention, thereis provided a joint device for a robot comprising a plurality of joints.In the joint device, at least rotational degrees of freedom incorrespondence with a roll axis, a pitch axis, and a yaw axis areprovided, and the yaw axis is offset in a roll axis direction from anaxis perpendicular to the roll axis and the pitch axis.

[0047] According to a twelfth aspect of the present invention, there isprovided a joint device for a robot comprising a plurality of joints. Inthe joint device, at least rotational degrees of freedom provided incorrespondence with a roll axis, a pitch axis, and a yaw axis areprovided, and the yaw axis is situated at a twisting location withrespect to both the roll axis and the pitch axis.

[0048] Other objects, feature, and advantages of the present inventionwill be made clear from the detailed description given in conjunctionwith the embodiment described below and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0049]FIG. 1 is a front view of a humanoid robot 100 of an embodiment ofthe present invention.

[0050]FIG. 2 is a back view of the humanoid robot 100 of the embodimentof the present invention.

[0051]FIG. 3 is a schematic view of a structural model showing thedegrees of freedom of the humanoid robot 100 of the embodiment of thepresent invention.

[0052]FIG. 4 is a schematic view of the structure of a control system ofthe humanoid robot 100 of the embodiment of the present invention.

[0053]FIG. 5 illustrates a structural model showing the degrees offreedom of the humanoid robot 100 of the embodiment of the presentinvention in the sagittal plane.

[0054]FIG. 6 is a schematic view showing the relationship between thepositions of left and right feet 22L and 22R and the positions of hipjoint yaw axes 16 when the hip joint yaw axes 16 are not offset fromcorresponding hip joint positions in the roll direction.

[0055]FIG. 7 is a schematic view showing the relationship between thepositions of the left and right feet 22L and 22R and the positions ofthe hip joint yaw axes 16 when the hip joint yaw axes 16 are not offsetfrom their corresponding hip joint positions in the roll direction.

[0056]FIG. 8 is an enlarged view of the crutch and a thigh section ofthe humanoid robot 100 when viewed from the sagittal plane.

[0057]FIG. 9 is an enlarged view of the crutch and the thigh section ofthe humanoid robot 100 when viewed from the front plane.

[0058]FIG. 10 illustrates a mechanism for offsetting a hip joint yawaxis 16.

[0059]FIG. 11 is a sectional view showing a state in which a screwingoperation has been performed at a location where a hip joint yaw axis 16is maximally offset from a lower limb in the roll axis direction.

[0060]FIG. 12 illustrates a coordinate system showing the direction ofmovement of the humanoid robot 100.

[0061]FIG. 13 schematically illustrates the structure of a humanoidrobot WABIAN which walks on two feet when viewed from the front plane.

[0062]FIG. 14 schematically illustrates the structure of the humanoidrobot WABIAN which walks on two feet when viewed in the sagittal plane.

[0063]FIG. 15 is a schematic view of the structure of the joint model ofa humanoid robot.

[0064]FIG. 16 is a schematic view of the structure of another jointmodel of a humanoid robot.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0065] Before disclosing a preferred embodiment of the presentinvention, the coordinate system used to express, for example, thedegrees of freedom of a robot in the specification will be defined.

[0066] In the embodiment, the direction of movement of the robot is usedto define the x axis. The horizontal direction towards the left or rightis used to define the y axis (with the horizontal direction towards theright being defined as the positive direction). The vertical directionis used to define the z axis. In the industry, in general, the xz planeis called the sagittal plane, whereas the yx plane in which the robotfaces the front is called the front plane.

[0067] As shown in FIG. 12, rotation around the direction of movement(that is, around the x axis) is called roll, rotation around thehorizontal direction towards the left or right (that is, around the yaxis) is called pitch, and the rotation around the vertical direction(that is, around the z axis direction) is called yaw.

[0068] A description of the embodiment will now be given in detail withreference to the drawings.

[0069]FIGS. 1 and 2 are a front view and a back view of a humanoid robot100 of the embodiment of the present invention. FIG. 3 is a schematicview of a structural model showing the degrees of freedom of thehumanoid robot 100 of the embodiment of the present invention.

[0070] As shown in FIG. 3, the humanoid robot 100 comprises upper limbsincluding two arms, a head 1, lower limbs including two legs for movingthe humanoid robot 100, and a trunk which connects the upper limbs andthe lower limbs.

[0071] The neck joint which supports the head 1 has three degrees offreedom produced in correspondence with a neck joint yaw axis 2, a neckjoint pitch axis 3, and a neck joint roll axis 4.

[0072] The arms each comprise a shoulder joint pitch axis 8, a shoulderjoint roll axis 9, an upper arm yaw axis 10, an elbow joint pitch axis11, a front arm yaw axis 12, a wrist joint pitch axis 13, a wrist jointroll axis 14, and a hand 15. Actually, each hand 15 has a structurewhich includes many joints/degrees of freedom and a plurality offingers. However, since the movements of the hands 15 only slightlycontribute to and affect the controlling of the posture and the walkingof the robot 100, it is assumed that each hand 15 has zero degrees offreedom. Therefore, each arm is defined as having seven degrees offreedom.

[0073] The trunk has three degrees of freedom produced in correspondencewith a trunk pitch axis 5, a trunk roll axis 6, and a trunk yaw axis 7.In the specification, the point where the trunk pitch axis 5 and thetrunk roll axis 6 intersect is defined as the location of the trunk.

[0074] The legs or the lower limbs each includes a hip joint yaw axis16, a hip joint pitch axis 17, a hip joint roll axis 18, a knee jointpitch axis 19, an ankle joint pitch axis 20, an ankle joint roll axis21, and a foot 22. In the specification, the point where each hip jointpitch axis 17 and its corresponding hip joint roll axis 18 intersect isdefined as the position of each hip joint. Actually, each foot 22 of thehuman body has a structure which includes a sole with many joints anddegrees of freedom. However, each sole of the humanoid robot 100 of theembodiment has zero degrees of freedom. Therefore, each leg isconstructed so as to have six degrees of freedom.

[0075] To sum up, the total number of degrees of freedom of the humanoidrobot 100 of the embodiment is 3+7×2+3+6×2=32. However, the number ofdegrees of freedom of the entertainment humanoid robot 100 is notnecessarily limited to 32. It is obvious that the number of degrees offreedom, that is, the number of joints can be increased or decreased asnecessary in accordance with, for example, the limiting conditions indesigning and manufacturing the robot and the required specification.

[0076] Each degree of freedom of the above-described humanoid robot 100is actually provided using an actuator. To respond to the demands ofapproximating the form of the robot to the natural form of a human beingby removing extra bulges from its external appearance, and ofcontrolling the posture of an unstable structure for walking on twofeet, it is preferable to use small and light actuators. In theembodiment, there are used in the humanoid robot 100 small AC(alternating current) servo actuators which are directly connected togears and incorporate in a motor unit a servo control system formed intoa one-chip system. This type of AC servo actuator is disclosed in, forexample, Japanese Application No. 11-33386 which has already beenassigned to the applicant.

[0077]FIG. 4 is a schematic view of the structure of a control system ofthe humanoid robot 100. As shown in FIG. 4, the humanoid robot 100comprises mechanical units 30, 40, 50R, 50L, 60R, and 60L, which areformed in correspondence with the head, the trunk, and the four limbs ofa human being. The humanoid robot 100 also comprises a control unit 80for performing a suitable controlling operation in order to achieveharmonious movements between each of the mechanical units 30, 40, 50R,50L, 60R, and 60L. (The R and L in 50R and 50L and in 60R and 60L standfor right and left, respectively. This also applies to the R and Lappearing in the reference numerals below.)

[0078] The movement of the entire humanoid robot 100 is generallycontrolled by the control unit 80. The control unit 80 comprises a maincontrol section 81 and a peripheral circuit 82. The main control section81 comprises main circuit components (not shown), such as a centralprocessing unit (CPU) and a memory. The peripheral circuit 82 includesan interface (not shown) for allowing transfer of data and commandsbetween, for example, a power supply circuit and each of the structuralelements of the robot 100.

[0079] For realizing the present invention, the location of placement ofthe control unit 80 is not particularly limited. Although, in FIG. 4,the control unit 80 is installed at the trunk unit 40, it may beinstalled at the head unit 30 or outside the humanoid robot 100. When itis installed outside the humanoid robot 100, communication with the bodyof the humanoid robot 100 may be carried out through wire or by radio.

[0080] Each degree of freedom of the humanoid robot shown in FIG. 3 isprovided using a corresponding joint actuator. More specifically, thehead unit 30 includes a neck joint yaw axis actuator A₂, a neck jointpitch axis actuator A₃, and a neck joint roll axis actuator A₄ disposedin correspondence with the neck joint yaw axis 2, the neck joint pitchaxis 3, and the neck joint roll axis 4, respectively.

[0081] The trunk unit 40 comprises a trunk pitch axis actuator A₅, atrunk roll axis actuator A₆, and a trunk yaw axis actuator A₇ disposedin correspondence with the trunk pitch axis 5, the trunk roll axis 6,and the trunk yaw axis 7, respectively.

[0082] The arm unit 5OR is divided into an upper arm unit 51R, an elbowjoint unit 52R, and a front arm unit 53R. The arm unit 50L is dividedinto an upper arm unit 51L, an elbow joint unit 52L, and a front armunit 53L. Each of the arm units 50R and 50L comprises a shoulder jointpitch axis actuator A₈, a shoulder joint roll axis actuator A₉, an upperarm yaw axis actuator A₁₀, an elbow joint pitch axis actuator A₁₁, anelbow joint roll axis actuator A₁₂, a wrist joint pitch axis actuatorA₁₃, and a wrist joint roll axis actuator A₁₄ disposed in correspondencewith its respective shoulder joint pitch axis 8, its respective shoulderjoint roll axis 9, its respective upper arm yaw axis 10, its respectiveelbow joint pitch axis 11, its respective elbow joint roll axis 12, itsrespective wrist joint pitch axis 13, and its respective wrist jointroll axis 14.

[0083] The leg unit 60R is divided into a thigh unit 61R, a knee unit62R, and a shin unit 63R. The leg unit 60L is divided into a thigh unit61L, a knee unit 62L, and a shin unit 63L. Each of the leg units 60R and60L includes a hip joint yaw axis actuator A₁₆, a hip joint pitch axisactuator A₁₇, a hip joint roll axis actuator A₁₈, a knee joint pitchaxis actuator A₁₉, an ankle joint pitch axis actuator A₂₀, and an anklejoint roll axis actuator A₂₁ disposed in correspondence with itsrespective hip joint yaw axis 16, its respective hip joint pitch axis17, its respective hip joint roll axis 18, its respective knee jointpitch axis 19, its respective ankle joint pitch axis 20, and itsrespective ankle joint roll axis 21.

[0084] Preferably, each of the actuators A₂ to A₂₁ is a small AC servoactuator (described above) which is directly connected to gears andwhich incorporates in a motor unit a servo control system formed into aone-chip system.

[0085] Subcontrol sections 35, 45, 55L and 55R, and 65L and R forcontrolling the driving of the corresponding actuators are disposed forthe head unit 30, the trunk unit 40, the arm units 50L and 50R, and theleg units 60L and 6R, respectively. Ground confirmation sensors 91 and92 for detecting whether or not the soles of the legs 60R and 60L havelanded on the floor are installed. A posture sensor 93 for measuring theposture is installed in the trunk unit 40.

[0086] The main control section 81 suitably controls the subcontrolsections 35, 45, 55L and 55R, and 65L and 65R in response to outputsfrom the sensors 91 to 93 in order to cause the upper limbs, the trunk,and the lower limbs of the humanoid robot 100 to move harmoniously. Inaccordance with, for example, user commands, the main control section 81sets the movements of the legs, the zero moment point (ZMP) path, themovement of the trunk, the movements of the upper limbs, the posture andheight of the waist, etc. Then, it sends commands for moving theabove-described parts of the body in accordance with the aforementionedsetting to each of the subcontrol sections 35, 45, 55L and 55R, and 65Land 65R. After the commands have been sent, each of the subcontrolsections 35, 45, 55L and 55R, and 65L and 65R interprets itscorresponding command received from the main control section 81 in orderto output a corresponding drive control signal to each of the jointactuators A₂ to A₂₁.

[0087]FIG. 5 illustrates a structural model showing the degrees offreedom of the humanoid robot 100 of the embodiment of the presentinvention when viewed from the sagittal plane. In order not tocomplicate FIG. 5, some of the joints shown in FIG. 3 have been omitted.In FIG. 5, the alternate long and short dashed line which extends in avertical direction in the plane of the sheet is defined as the trunkaxis, that is, the vertical axis which passes through substantially thecenter of gravity of the humanoid robot 100.

[0088] A first feature of the humanoid robot 100 of the embodiment is amechanism which makes it possible to arbitrarily set the offsetlocations of the hip joint yaw axes 16 from the corresponding hipjoints, that is, the offset location of the trunk from the lower limbsin the roll axis direction.

[0089] Here, the locations of the hip joints are defined as the pointswhere the corresponding hip joint pitch axes 17 and the correspondinghip joint roll axes 18 intersect each other (as described above). As canbe seen from FIG. 5, the amount of offset of each hip joint yaw axis 16in the roll axis direction defines the location where each lower limb ismounted with respect to its corresponding upper limb. When the hip jointyaw axis 16 mounting locations are not offset, in the sagittal plane thelines passing through the hip joint locations and the corresponding hipjoint yaw axes 16 are lined up in the vertical direction, that is, in astraight line in the yaw axis direction of the entire robot 100. Incontrast to this, in FIG. 5, the hip joint yaw axes 16 are offset, sothat they are separated upward in the vertical direction from theircorresponding hip joint locations by the corresponding offset amounts.

[0090] The humanoid robot 100 which is used to help people in life orwhich is constructed so as to be closely connected to life is used in aninfinite variety of ways. For example, the humanoid robot 100 may beused to carry baggage with one or both arms, or to hold a heavy objectin both arms, or to carry a bag on the shoulder. In these cases, thelocation of the center of gravity changes considerably. Since the offsetamount of each hip joint yaw axis 16 from its corresponding hip jointlocation can be adjusted, it is possible to accommodate to the effect ofchanges in the location of the center of gravity, so the weights of theupper and lower limbs can be flexibly balanced.

[0091] When each hip joint yaw axis 16 is offset from its correspondinghip joint location in the roll axis direction, the hip joints can bemade more compact in size.

[0092] Although the actuators A₂ to A₂₁ which produce theircorresponding degrees of freedom of the humanoid robot 100 are AC servoactuators (described above) which are directly connected to gears sothat they are smaller than other types of servo actuators, the actualdimensions of these actuators are in the direction of the axis ofrotation or the radial direction of the actuators. Regarding the hipjoint yaw axes 16, the yaw axis actuators A₁₆ increase the dimensions ofthe hip joints in the height directions.

[0093] If a hip joint yaw axis 16 is disposed so as to intersect atright angles to its corresponding hip joint location, the size of thecrutch of the humanoid robot 100 is equal to the sum of the diameters(assumed to be 2D) of the actuators A₁₇ and A₁₈ (formed incorrespondence with the respective hip joint pitch axis 17 and therespective hip joint roll axis 18) and the longitudinal dimension(assumed to be L) of the hip joint yaw axis actuator A₁₆. Therefore, thesize of the crutch of the humanoid robot 100 is equal to 2D+L.Consequently, the dimensions of the mechanical units are no longer inproportion or balanced with respect to each other. On the other hand,when each of the hip joint yaw axis 16 is offset, the height of theportion of the humanoid robot 100 corresponding to the waist can be madesmaller than 2D+L, making it possible to form the humanoid robot 100whose mechanical units are dimensionally proportioned with respect toeach other. In other words, it is possible to form the humanoid robot100 which has a proportioned appearance very close to the natural formof the human body. This point will be discussed later with reference toFIG. 8.

[0094] When the hip joint yaw axes 16 are offset in the roll axisdirection from their corresponding hip joint locations, it is alsopossible to prevent interference between the left and right feet (when,in particular, the feet are rotated to change direction) when the robot100 is walking. This point will hereunder be described with reference toFIGS. 6 and 7. In general, a robot which walks on two feet changesdirection by rotating a foot or an ankle in a desired direction ofchange in order to advance the ankle in the desired direction of change.

[0095] When the hip joint yaw axes 16 are not offset from theircorresponding hip joint locations, that is, when the hip joint locationsand the corresponding hip joint yaw axes 16 are lined up vertically orin a straight line in the yaw axis direction, the load is concentratedat a particular location, so that the location of the center of gravityof the whole humanoid robot 100 is confined near the hip joint yaw axes16. Therefore, as shown in FIG. 6, in order to ensure that the robot 100walk stably, that is, in order to achieve stability in the pitchdirection, the left and right ankles must be mounted so that they aresubstantially aligned with the centers of feet 22R and 22L.

[0096] By rotating the foot in the desired direction of change andadvancing the foot forward, the robot of the type walking on two feetcan change direction. Specifically, this foot is rotated around itscorresponding hip joint yaw axis 16. When this hip joint yaw axis 16 isnot offset from its corresponding hip joint location, the center ofrotation of the foot is substantially aligned with the center of theankle. In the base where, as shown in FIG. 6, the ankles aresubstantially aligned with the centers of the corresponding feet, whenone of the feet is rotated, its heel interferes with the other foot,making it impossible to change direction at predetermined extremeangles.

[0097] It is possible to prevent interference (illustrated in FIG. 6)between the left and right feet by increasing the width of the crutch,that is, the distance between the right leg unit 60R and the left legunit 60L. However, when the bipedal robot has a wider crutch, the centerof gravity moves considerably horizontally towards the left and rightwhile it is moving or walking, though its posture becomes more stablewhen it is not walking. Therefore, it becomes considerably difficult tocontrol the posture of the robot as a result of the action of theinertial moment.

[0098] In contrast, when, as shown in FIG. 5, the hip joint yaw axes 16are offset from their corresponding hip joint locations in the backwarddirection or in the direction opposite to the direction of movement, theload spreads, so that the center of gravity of the entire humanoid robot100 is located forwardly from the hip joint yaw axes 16. Since the hipjoint yaw axes 16 are offset from their corresponding hip jointlocations, the centers of rotation of the left and right feet aredisposed behind their corresponding ankles.

[0099] In this case, even if one of the hip joint yaw axis 16 is rotatedfor changing direction, it is possible to reduce interference betweenthe feet 22R and 22L. In other words, since it is not necessary toincrease the width of the crutch, posture control can be easily carriedout to cause the robot to walk stably on two feet.

[0100] A second feature of the humanoid robot 100 of the embodiment isanother mechanism which makes it possible to arbitrarily set the offsetlocations of the hip joint yaw axes 16 from the upper part of the body,that is, from the trunk in the roll axis direction.

[0101] The location of the trunk in the embodiment is defined as thepoint where the trunk pitch axis 5 and the trunk roll axis 6 intersect.(However, judging from the gist of the present invention, the locationof the trunk should not be defined in a restrictive sense. It should bedefined by comparison with the mechanisms of, for example, human beingsand monkeys.) As can be understood from FIG. 5, the offset amount ofeach of the hip joint yaw axis 16 in the roll axis direction defines thelocation of mounting of the upper part of the body onto the lower limbs.When the hip joint yaw axis 16 mounting locations are not offset, in thesagittal plane the location of the trunk and the hip joint yaw axes 16are lined up vertically, that is, in a straight line in the yaw axisdirection of the entire robot 100. In contrast, the hip joint yaw axes16 are, as shown in FIG. 5, offset downward in the vertical directionfrom the location of the trunk by the offset amounts.

[0102] As already mentioned, the humanoid robot 100 which is used tohelp people in life and which is produced so as to be closely connectedto human life is used in an infinite variety of ways. In addition, thelocation of the center of gravity of the humanoid robot 100 changesconsiderably in accordance with its mode of use. Since the offsetamounts of the hip joint yaw axes 16 from the location of the trunk canbe adjusted, it is possible to accommodate to the effect of the movementof the center of gravity in order to flexibly balance the weights of theupper and lower limbs. As a result, it is possible to easily make therobot 100 which has a structure whose center of gravity is situated at arelatively high location walk stably while it is in an erect posture.

[0103] The basic movement of a human being walking on two feet is basedon a forwardly tilted posture. In other words, it is easier to make arobot exhibit the natural movement of a human being when the trunk whichcorresponds to the waist of a human being is disposed towards the front.The humanoid robot 100 of the embodiment can faithfully emulate thewalking of a human being by offsetting the hip joint yaw axes 16 fromthe location of the trunk in the roll axis direction.

[0104] By offsetting the hip joint yaw axes 16 and moving the locationof the center of gravity of the entire robot 100 slightly forward, therobot 100 can easily balance itself in terms of its weight while it iswalking or moving.

[0105]FIG. 8 is an enlarged view of the crutch and the thigh section ofthe humanoid robot 100 when viewed in the sagittal plane. FIG. 9 is anenlarged view of the crutch and the thigh section of the humanoid robot100 when viewed from the front plane.

[0106] As shown in FIGS. 8 and 9, a hip joint pitch actuator A₁₇ and ahip joint roll axis actuator A₁₈ are mounted onto a thigh unit 61. Eachhip joint yaw axis actuator A₁₆ is mounted onto a bracket (a pelvis atthe trunk side) 61′.

[0107] In the conceptual diagram of FIG. 5, the hip joint pitch axis 17and the hip joint roll axis 18 intersect at right angles to each other.However, actually, the actuators A₁₇ and A₁₈ which have a large volumecannot be disposed so that their axes of rotation intersect at rightangles to each other. Accordingly, in the embodiment, as shown in FIGS.8 and 9, the robot 100 is constructed so that the actuator A₁₇ whichincludes one of the axes that intersects at right angles is disposedaway from the pitch axis 17, and so that the driving power istransmitted to the pitch axis 17 by a pulley transmission system inorder to make the pitch axis and the roll axis intersect each other.

[0108] As can be seen from FIG. 8, in the humanoid robot 100 of theembodiment, an offset O₁ of a hip joint yaw axis 16 from itscorresponding hip joint location, and an offset O₂ of the location ofthe trunk from the hip joint yaw axis 16 are set.

[0109] As already discussed, weight balancing and the controlling of theposture can be easily carried out by providing the offsets O₁ and O₂.

[0110] When a trunk pitch axis actuator A₅ is disposed in the locationas shown in FIG. 8, the distance between the corresponding trunk rollaxis 6 and the corresponding trunk joint roll axis 18 becomes H₁. On theother hand, when the offset O₂ is not set, that is, when the offset O₂is zero, the trunk pitch axis actuator A₅ can only be disposed at thelocation marked by dotted lines in FIG. 8. As a result, the distancebetween the trunk roll axis 6 and the hip joint roll axis 18 isincreased to H₂ as shown in FIG. 8. This means that the height of thewaist of the humanoid robot 100 becomes larger, so that whole humanoidrobot 100 is not longer well proportioned. Conversely speaking, bysetting the offset O₂ as in the embodiment, the whole humanoid robot 100can be kept well proportioned.

[0111]FIG. 10 is an enlarged view of mounting parts around the hipjoints.

[0112] As described above, the hip joint pitch axis actuators A₁₇ andthe hip joint roll axis actuators A₁₈ are mounted onto the thigh units61L and 61R. The hip joint yaw axis actuators A₁₆ are mounted onto thebracket (pelvis at the trunk side) 61′. As shown in FIG. 10, the thighunit 61 and the bracket (pelvis at the trunk side) 61′ are screwedthrough four threaded holes in a hip joint variable mounting section61-1. As shown in FIG. 10, the threaded holes are in the form of slotswhich extend in the offset direction, so that the offset location of thehip joint yaw axis 16 from its corresponding lower limb can be freelyset in accordance with the locations of screwing.

[0113]FIG. 11 is a sectional view showing a state in which a screwingoperation has been performed at a location where a hip joint yaw axis 16is maximally offset from the corresponding lower limb in the roll axisdirection.

[0114] The trunk unit 40 (not shown in FIG. 11) and the bracket (pelvisat the trunk side) 61′ are screwed through four threaded holes of atrunk variable mounting section 61-2. As shown in FIG. 11, since thethreaded holes are in the form of slots which extend in the offsetdirection, the offset location of the hip joint yaw axis 16 with respectto its corresponding upper limb can be easily set in accordance with thescrewing locations.

[0115] The present invention has been described in detail with referenceto a particular embodiment of the present invention. However, it isobvious that modifications and substitutions may be made by thoseskilled in the art without departing from the gist of the presentinvention.

[0116] In the description of the specification, for convenience sake,the point of intersection of the trunk pitch axis 5 and the trunk rollaxis 6 is defined as the location of the trunk, and the point ofintersection of a hip joint pitch axis 17 and a trunk joint roll axis 18is defined as the location of a hip joint. However, the meanings of thephrases “the location of the trunk” and “the locations of the hipjoints” are to be flexibly interpreted by comparing the body mechanisms,such as the joint structures, of an actual human being and those of thehumanoid robot 100. Similarly, the meaning of the term “body axis” whichmeans the vertical center axis of the body is to be flexiblyinterpreted.

[0117] The gist of the present invention is not necessarily limited to arobot. In other words, the present invention may be similarly applied toany product, such as a toy, belonging to other industrial fields as longas the product is a mechanical device which moves in such a way as toemulate the movement of a human being by the use of electrical andmagnetic actions.

[0118] In short, the embodiment used to disclose the present inventionhas been described for illustrative purposes only. Therefore, it is tobe understood that the present invention is not limited thereto. Inorder to determine the gist of the present invention, one should referto the claims of the present invention.

[0119] For reference, a joint model structure of a humanoid robot isillustrated in FIG. 15. In the joint model structure shown in FIG. 15,the section of the robot which extends from shoulder joints 5 to hands 8so as to include upper arms 3, elbow joints 6, front arms 4, and wristjoints 7 is called upper limb section 17. The section of the robot whichextends from the shoulder joints 5 to trunk joints 10 is called a trunk9, which corresponds to the trunk of a human being. The section of therobot which extends from hip joints 11 to the trunk joint 10 is calledwaist 18. The trunk joint 10 acts to produce the degrees of freedom thatthe backbone of a human being possesses. The section of the robotcomprising parts below the hip joints 11, that is, thighs 12, kneejoints 14, lower crura 13, ankle joints 15, and feet 16 is called lowerlimb section 19. In general, the part of the body above the trunk joint10 is called the upper part or upper half of the body, whereas the partof the body below the trunk joint 10 is called the lower part or lowerhalf of the body.

[0120] Another joint model structure of a humanoid robot is illustratedin FIG. 16. This joint model structure shown in FIG. 16 differs fromthat shown in FIG. 15 in that it does not possess the trunk joint 10.(Refer to FIG. 16 for the names of the different parts of the humanoidrobot.) Since the humanoid robot does not include the trunk joint whichcorresponds to the backbone of a human being, the movement of the upperpart of the humanoid robot cannot be moved like a human being. However,when an industrial humanoid robot for carrying out dangerous tasks orfor carrying out tasks in place of human beings is used, the industrialhumanoid robot is sometimes not constructed so as to move the upper partof its body. The reference numerals used in FIGS. 15 and 16 do notcorrespond to those in the figures other than FIGS. 15 and 16.

[0121] As can be understood from the foregoing description, according tothe present invention, it is possible to provide an excellent humanoidrobot having a structure which emulates the mechanisms and the movementsof the human body.

[0122] According to the present invention, it is possible to provide anexcellent leg-movement-type humanoid robot which walks on two feet, andwhich includes what is called the upper half of the body formed on thelegs, including the trunk, the head, and the arms.

[0123] According to the present invention, it is also possible toprovide an excellent humanoid robot which can move naturally in a wayclose to that of a human being and in a way sufficiently indicative ofemotions and feelings with considerable fewer degrees of freedom thanthe human body.

[0124] The humanoid robot of the present invention is aleg-movement-type robot which walks on two feet using the lower limbsand which comprises upper limbs, lower limbs, and a trunk. In thehumanoid robot, the hip joints which join the lower limbs and the trunkpossess degrees of freedom produced by their corresponding hip joint yawaxes, their corresponding hip joint roll axes, and their correspondinghip joint pitch axes. The hip joint yaw axes can be arbitrarily offsetin the roll axis direction.

[0125] Therefore, it is possible to flexibly balance the weights of theupper and lower limbs by accommodating to the effects of the movement ofthe center of gravity occurring as a result of changing the mode of useof the robot.

[0126] By offsetting the hip joint yaw axes, the height of the waist,that is, the length of the portion of the robot corresponding to thewaist can be decreased, so that it is made more compact in size, makingit possible to form a humanoid robot whose various mechanical units aredimensionally proportioned with respect to each other, that is, ahumanoid robot having an external appearance which is close to thenatural form of the human body.

[0127] When the hip joint yaw axes are offset from their correspondinghip joint locations in the backward direction or in the directionopposite to the direction of movement, the center of gravity of thehumanoid robot is situated forwardly of the hip joint yaw axes.Therefore, in order to ensure stability in the pitch direction, the leftand right ankles are disposed behind the centers of the correspondingfeet. In this case, even if one of the hip joint yaw axis is rotated tochange the direction of the corresponding foot, interference between theleft and right feet (such as the striking of the heel of one of the feetwith the other foot as shown in FIG. 6) can be reduced.

[0128] The humanoid robot can faithfully emulate the basic movements ofa human being which walks on two feet, the basic movements being basedon a forwardly tilted posture.

[0129] By performing an offsetting operation in order to move thelocation of the center of gravity of the entire robot slightly forward,the robot can easily balance itself it terms of its weight while walkingor moving.

What is claimed is:
 1. A leg-movement-type robot which moves using lowerlimbs, comprising: at least the lower limbs and a trunk; wherein a hipjoint which connects the lower limbs and the trunk possesses at least adegree of freedom in correspondence with a hip joint yaw axis which isincluded in the hip joint; and wherein the leg-movement-type robotfurther comprises: an offset setting mechanism for arbitrarilyoffsetting the hip joint yaw axis from the hip joint in a roll axisdirection.
 2. A leg-movement-type robot which moves using lower limbs,comprising: at least the lower limbs and a trunk; wherein a hip jointwhich connects the lower limbs and the trunk possesses at least a degreeof freedom in correspondence with a hip joint yaw axis which is includedin the hip joint; and wherein the hip joint yaw axis is offset from thehip joint in a roll axis direction.
 3. A leg-movement-type robot whichmoves using lower limbs, comprising: at least the lower limbs and atrunk; wherein a hip joint yaw axis used for changing the direction of afoot tip is offset from the location of a hip joint used for walkingusing the feet.
 4. A leg-movement-type robot which moves using lowerlimbs, comprising: at least the lower limbs and a trunk; wherein a hipjoint which connects the lower limbs and the trunk possesses at least adegree of freedom in correspondence with a hip joint yaw axis which isincluded in the hip joint; and wherein the leg-movement-type robotfurther comprises: an offset setting mechanism for arbitrarilyoffsetting the hip joint yaw axis from the trunk in a roll axisdirection.
 5. A leg-movement-type robot which moves using lower limbs,comprising: at least the lower limbs and a trunk; wherein a hip jointwhich connects the lower limbs and the trunk possesses at least a degreeof freedom in correspondence with a hip joint yaw axis which is includedin the hip joint; and wherein the hip joint yaw axis is offset from thetrunk in a roll axis direction.
 6. A leg-movement-type robot which movesusing lower limbs, comprising: at least the lower limbs and a trunk;wherein a hip joint yaw axis used for changing the direction of a foottip is offset from the trunk.
 7. A leg-movement-type robot which movesusing lower limbs, comprising: at least the lower limbs and a trunk;wherein the trunk is offset from the lower limbs in a roll axisdirection.
 8. A leg-movement-type robot which moves using lower limbs,comprising: upper limbs; the lower limbs; and a trunk; wherein the upperlimbs are offset from the lower limbs in a roll axis direction.
 9. Arobot of a type which spreads the legs thereof based on rotationaldegrees of freedom provided in correspondence with a hip joint rollaxis, a hip joint pitch axis, and a hip joint yaw axis, wherein at leastthe lower limbs and a trunk are mounted substantially vertically along abody axis direction, and wherein the hip joint yaw axis is offset fromthe body axis by a predetermined amount.
 10. A robot of a type whichspreads the legs thereof based on rotational degrees of freedom providedin correspondence with a hip joint roll axis, a hip joint pitch axis,and a hip joint yaw axis, wherein at least lower limbs and a trunk aremounted substantially vertically along a body axis direction, andwherein the hip joint yaw axis is offset from the body axis by apredetermined amount in a negative roll axis direction.
 11. A jointdevice for a robot comprising a plurality of joints, wherein at leastrotational degrees of freedom in correspondence with a roll axis, apitch axis, and a yaw axis are provided; and wherein the yaw axis isoffset in a roll axis direction from an axis perpendicular to the rollaxis and the pitch axis.
 12. A joint device for a robot comprising aplurality of joints, wherein at least rotational degrees of freedomprovided in correspondence with a roll axis, a pitch axis, and a yawaxis are provided, and wherein the yaw axis is situated at a twistinglocation with respect to both the roll axis and the pitch axis.